The present invention relates generally to pressure transmitters for use with industrial processes. In particular, this invention relates to an isolator system used in pressure transmitters.
Isolator systems in pressure transmitters use a relatively inert isolator liquid that couples pressure from a process fluid to a pressure sensor. This is necessary because pressure sensors are not generally designed to withstand direct contact with a process fluid. A flexible isolator diaphragm separates the process fluid from the isolator liquid, which is typically silicone oil. Tubes and passageways that are filled with the oil are used to couple pressure from the isolator diaphragm to the pressure sensor. Isolator systems prevent process fluids from contacting and interfering with the operation of the pressure sensor.
The oil-filled tubes and passageways are kept narrow to reduce the quantity of oil used in the isolator system and limit the pressure effects due to thermal expansion and contraction of the oil. The narrow passageways, however, may restrict the flow of oil and slow down the response of the pressure sensor. An isolator system is desired that has a low isolator liquid volume but which does not inhibit rapid response of the pressure sensor.